For more than 60 years the particle-in-cell (PIC) technique [1]} has been used to simulate a wide variety of physical problems, ranging from electrical discharge to particle acceleration. However, in several scenarios - in particular field ionisation or QED cascades - the number of particles in the simulation box grows exponentially. Due to an overwhelming number of particles, the associated memory required can easily exceed that available on even high performance computers and as a consequence the computational performance drops drastically.
